Ordinance firing device



Sept. 26, 1967 J. 5. BARRETT 3,343,490

ORDINANCE FIRING DEVICE 'Filed Aug. 12, 1966 2 Sheets-Sheet 1 FIG.1

INVENTOR. germ S. BARRETT 'CDBQD ggvlglmmm i YATTY.

Sept. 26, 1967 J. s. BARRETT 3,343,490-

ORDINANCE FIRING DEVICE 2 Sheets-Sheet 2 Filed Aug. 12, 1,966

FIG. INVENTOR.

JOHN S. BARRETT United States Patent 3,343,490 ORDINANCE FIRING DEVICE John S. Barrett, Chagrin Falls, Ohio, assignor to Lear Siegler, Inc., Santa Monica, Calif., a corporation of Delaware Filed Aug. 12, 1966, Ser. No. 572,005 3 Claims. (Cl. 102--70) This application pertains to an apparatus for firing a detonatable device, and, more particularly, to a solenoid operated apparatus whereby the firing pin of the apparatus imparts suflicient energy to the detonator to fire the device.

In the firing of a detonatable device there is a requirement that the detonator be struck with suflicient energy to fire the primer of the device. This energy is imparted to the primer by the firing pin of the firing apparatus, and has a direct relationship to the mass of the pin times the square of its velocity. The maximization of the transmitted energy has been limited by two characteristics of the solenoid firing device. The first characteristic is the inverse relationship between the armatures velocity and mass, whereby a desired increase in one necessitates a decrease in the other. The second is that the firing pin has been an integral part and direct extension of the solenoids armature. Since energy is directly related to both velocity and mass, these are undesirable characteristics. Because of the dominant effect of velocity in the energy equation, attempts to minimize these limiting characten'stics, while maximizing the energy level of the firing pin, have centered on increasing its velocity.

These attempts are occasioned by the numerous advantages inherent in solenoid actuated firing devices. Some of these advantages include the elimination of the need for mechanical linkage between the firing device and the person initiating the firing, thus facilitating remote operation of the firing device. Also, since the in- ..itiating energy is'derived from an electrical signal, it enables the paralleling of firing devices allowing multiple firings from a single command. But perhaps the greatest advantage inherent in solenoid operated devices is their fast response. This is of increasing importance in this age where targets can move at supersonic speeds. These and other advantages have made it a worthwhile endeavor to remove the limitations and further improve the performance of solenoid firing devices.

Many prior devices have attempted to increase the velocity of the firing pin without attempting to remove its limiting factors. Some of the methods employed include: increasing the saturation current in the solenoid coil by means of increasing the voltage applied to the coil; using a condenser and switching device to create a large initial surge of current in the solenoid coil; and the use of two coils in series, with switching means to affect a large initial magnetic field. Another technique formerly used involved increasing the magnetic flux by choice of materials, their configuration and construction. These modifications, while useful, add to the size, weight and cost of the device while failing to remove its original limitations.

The principal object of this invention is, therefore, the provision of an improved apparatus for firing detonatable devices wherein the velocity of the firing pin is not limited to the velocity of the armature of the electromechanical device.

Another object of this invention is to provide an apparatus for firing detonatable devices wherein the firing force generated by electromechanical means is more efficiently transmitted to the firing pin of the apparatus.

A further object of this invention is to provide an apparatus for firing detonatable devices wherein the firing pin moves at a velocity greater than the velocity of the flCe armature of the electromechanical means generating the firing force.

A still further object of this invention is to provide an apparatus for firing detonatable devices wherein the increase of velocity of the firing pin over the velocity of the armature of the electromechanical means is accomplished by a hydraulic amplifier.

The manner in which these and other objects and advantages of the invention are obtained will be apparent from the following detailed description of a presently preferred embodiment, illustrated in the accompanying drawings, forming a part of this application, and in which:

FIG. 1 is a view, partially in section, of the solenoid apparatus, in its unenergized position, illustrating its use in combination with an ordinance barrel and cartridge;

FIG. 2 is an enlarged view of a portion of FIG. 1; and

FIG. 3 is a view similar to FIG. 2 shown as it appears when the solenoid is in an energized position.

Structural description As best seen in FIG. 1, the preferred embodiment of this invention includes a solenoid apparatus 10, upon which a barrel 11 is threadably mounted. Barrel 11 contains a detonatable cartridge 12. Although shown in combination with a particular type of ordinance barrel 11, it will be obvious that the invention will have usefulness with barrels having swinging breeches and other types of ordinance devices.

Within and as a part of the solenoid apparatus 10 is an annular coil 13 which is wound about an insulating tspool 14. Lead wires 15 of coil 13 are connected to a source of direct current by plug 16. It is to be understood that this invention is also adaptable for use in alternating current solenoids. Spool 14 has a cylindrical passageway 17 extending axially through its center. A soft iron core 18 is mounted in the forward part of passageway 17 and is bonded to spool 14. Core 18 has a radially extending positioning flange 19 which abuts the forward end of spool 14, and an annular extended portion 46. Coil 13 and flange 19 are received internally of an outside cylindrical casing 20. At the rearward end of spool 14 is an annular block 21 with an annular sleeve 22 extending in the rearward direction. The block 21 and sleeve 22 have extending therethrough a cylindrical passageway 23, of the same diameter as and coaxial with passageway 17.

A cap 24 is mounted at the rearward end of sleeve 22 and in sealing contact with casing 20, whereby the rearward end of opening 23 is terminated. Cap 24 is maintained in said sealing contact by the extended portion 25 of casing 20, said portion 25 being sufficiently crimped to maintain said contact.

An armature 26, having a generally cylindrical configuration, also constructed of soft iron, is slidably mounted within the cylindrical passageway 23. Armature 26 has a central cylindrical passageway 27 extending therethrough coaxial with passageway 23. The rearward end of passageway 27 is tapped to receive a set screw 28. A spring 29 mounted in passageway 27 extends from the set screw 28 out the forward end of the passageway 27 to the core 18. The function of spring 29 is to urge the armature 26 away from the core 18 and maintain an air gap therebetween. The forward end of armature 26 is of such a design that, upon energization of coil 13, the force of spring 29 is overcome, thereby closing the air gap be tween the armature 26 and the core 18 and causing the adjacent surfaces of core 18 and armature 26 to engage in full mating contact. The particular configuration of the adjacent engaging surfaces of core 18 and armature 26 as shown in FIG. 1 is chosen to establish maximum electromagnetic attraction between the two segments, as will be appreciated by those skilled in the art; however, any suitable design can be used.

Core 18 has formed within it a passageway comprised of two portions coaxial with the axis of said core. The first portion 30, located rearward of the other portion 31 is a cylindrical passageway of smaller diameter than the portion 31. Portion 31 contains the components which cause velocity amplification and is designated the velocity amplifying chamber.

In describing the velocity amplifying chamber 31, reference will be made to FIG. 2. The principal component of chamber 31 is a metallic block 32 internally machined to form two connecting chambers 33 and 34. The larger chamber 33 communicates with the smaller 34 by a conically shaped reducing portion 35. Chamber 33 contains a slidable piston 36 mounted on the forward end of a piston rod 37 slidably mounted in the core passageway portion 30. Piston rod 37 extending in a rearward direction through passageway 36) in core 18 bridges the air gap between core 18 and armature 26 and extends into passageway 27. Chamber 34 contains a firing pin 38 axially slidably mounted in chamber 34. Firing pin 38 is comprised of a cylindrical member 47 extending through a circularly formed flange 48. Filling the volume between the piston 36 and the firing pin 38 is an incompressible hydraulic fluid 39. Rubber seals 40 and 41 are mounted on the shafts of piston rod 37 and firing pin 38 respectively. Seal 40 is bonded to piston rod 37 at surface 42. This seal is positioned and secured by the interaction of collar 43 and block 32. Seal 41 is similarly bonded to pin 38 at surface 44-. It is secured and positioned by the interaction of block 32 and cap 45. These seals 40 and 41 perform the dual function of containing fluid 39 within the chambers, and also urging the piston 36 and firing pin 38 from their energized position as shown in FIG. 3 to their unenergized position as shown in FIG. 2. Cap 45 also performs a dual purpose. In conjunction with seal 41, cap 45 serves as a limit on the axial movement of firing pin 38 by engaging flange 48. Cap 45 is also used to protect the velocity chamber 31 from the effects of detonating the primer of cartridge 12.

Operating description FIG. 1 shows solenoid apparatus 10, in its unenergized position. In this position the air gap between core 18 and armature 26 is maintained at a maximum by spring 29. Piston 36 and firing pin 38 are positioned at the rearward ends of their respective chambers by the recovery action of seals 40 and 41 respectively. To initiate the firing of the detonatable device a direct current signal is applied to the coil 13, causing a current to flow in the coil thereby producing a force field around the coil. The lines of flux of this force field create an electromagnetic attraction between armature 26 and core 18 suflicient to overcome the force of spring 29 and close the air gap. As the arma ture 26 moves forward to mate with the core 18 set screw 28 contacts the end of piston rod 37 slidably driving it in an axial direction. The amount of travel of piston rod 37 can be predetermined by adjustment of set screw 28. The contemporaneous movement of piston 36 mounted on the other end of piston rod 27 displaces the fluid 39 in chamber 33 at a velocity equal to the velocity of the armature. As the piston 36 moves forward in chamber 33 the fluid 39 is driven through reducing portion 35 into the smaller chamber 34- with a resulting amplification of the velocity of the fluid 39. The resulting amplification of the velocity of fluid 39 is equal to the ratio of the cross sectional area of chamber 33 to the cross sectional area of chamber 34. A force is transmitted to firing pin 38 by the fluid 39 and the firing pin 38 is driven at the amplified velocity of the fluid 39. The force and velocity thus imparted to the firing pin 38 is sufiicient to fire the primer of the cartridge 12.

Immediately after firing, the direct current signal to coil 13 is discontinued, resulting in a collapsing of the force field and the elimination of the attraction between core 18 and armature 26. The force of spring 29 is sufficient to reestablish the air gap between core 18 and armature 26. This allows seals 40 and 41, by virtue of internal elastic recovery forces, to restore piston 36 and firing pin 38, respectively, to their unenergized positions. It should be noted that in the particular application with reference to which this invention is described, the recovery time of the apparatus 10 is not critical. If it were critical, well known piston and firing pin return means, such as springs, could be utilized.

Although the apparatus has been described with reference to a specific embodiment thereof, it will be understood to those skilled in the art to which it pertains that further modifications and refinements within the spirit and scope of the appended claims may be made thereto.

I claim:

1. An apparatus for firing a detonatable device, comprising fluid linear displacement means; fluid velocity amplifying means, a linearly displaceable firing pin; incompressible fluid means contained within said fluid velocity amplifying means and between said displacement means and said firing pin, whereby linear displacement of said fluid by said displacement means causes said firing pin to be linearly displaced a distance greater than the linear displacement of said fluid displacement means.

2. An apparatus for firing a detonatable device, comprising a fluid velocity amplifying means, said amplifying means having two cylindrically shaped chamber defining portions in communication with one another, the first portion having a greater cross sectional area than the second portion; a linearly movable fluid displacement means; an axially displaceable firing pin slidably mounted in said second portion; incompressible fluid means contained within said amplifying means in communication with and between said fluid displacement means and said firing pin, whereby linear displacement of said fluid by said displacement means from said first portion to said second portion causes said firing pin to be displaced at a greater velocity than that of said fluid linear displacement means.

3. An apparatus for firing a detonatable device, comprising a fluid velocity amplifying means, said amplifying means having two cylindrically shaped fluid containing portions in communication with one another, the first portion being of greater cross sectional area than the second portion; a piston axially movably mounted in the said first portion; a firing pin axially movably mounted in the said second portion; a cylindrical core having a passageway formed axially therethrough; an armature mounted within said apparatus for movement toward and away from said core, having a passageway formed axially therethrough and in axial alignment with the passageway of said core; resilient means for normally maintaining separation between said core and said armature; a piston rod axially movably mounted in the passageway of said core having one end extending into the passageway of said armature and the other end thereof attached to said piston; adjustable means contained within the passageway of said armature to engage and move said piston rod when said armature is moved toward said core; energizable moving means to move said armature toward said core; and incompressible fluid means contained within said amplifying means between said piston and said firing pin whereby said firing pin is moved at a greater velocity than the axial velogity of said piston when said moving means is energize No references cited.

SAMUEL FEINBERG, Primary Examiner. G. H. GLANZMAN, Assistant Examiner. 

1. AN APPARATUS FOR FIRING A DETONATABLE DEVICE, COMPRISING FLUID LINEAR DISPLACEMENT MEANS; FLUID VELOCITY AMPLIFYING MEANS, A LINEARLY DISPLACEABLE FIRING PIN; INCOMPRESSIBLE FLUID MEANS CONTAINED WITHIN SAID FLUID VELOCITY AMPLIFYING MEANS AND BETWEEN SAID DISPLACEMENT MEANS AND SAID FIRING PIN, WHEREBY LINEAR DISPLACEMENT OF SAID FLUID BY SAID DISPLACEMENT MEANS CAUSES SAID FIRING 